1. Field of Invention
The invention relates to a method for producing a structure pursuant to the generic part of claim 1. Such methods are in particular developed as lithographic processes and are preferably used for the production of two-dimensional or three-dimensional microstructures or micro-optics, for example in semiconductor technology or in photonics.
In such processes, the write field specified by the exposure device is frequently smaller than the total structure to be obtained. To produce an expanded structure, the entire structure is therefore sliced into partial structures, which are written consecutively. For this purpose, the relative position of the write field is changed in steps on the substrate surface and a partial structure is respectively written in one position of the write field.
Therefore, the different partial structures must be positioned precisely and be placed against each other reciprocally aligned.
2. Description of Related Art
As, on the one hand, it is already known to arrange the substrate and/or the exposure device highly precisely in work tables that can be displaced in two dimensions. Such high precision tables can be monitored and controlled by means of interferometric measuring devices. Such type of devices are expensive in terms of engineering, however, and frequently require exact control and stabilization of the ambient operating conditions, which can make this procedure expensive.
It is moreover known to examine the positioning of the write field for writing the respective partial structures with the aid of reference structures and correct the positioning in the event of deviation, if necessary. For example, DE 10 2006 036 172 A1 within the meaning of the generic part of claim 1, describes to calibrate the displacement of the write field before the substrate by using an adjustment structure that is coupled with the work table. In this instance, the adjustment structure is provided separately from the substrate to be processed, i.e. it will not be generated on the substrate itself.
In the prior art is also known to carry out the actual method for producing a structuring with specially prepared substrates, on which an expanded reference structure is already defined. Such type of reference structure remains permanently on the substrate, however, and consists frequently of another material than the structuring to be obtained. In this respect, the reference structure can be an interference here. The rendering and form of the reference structure is furthermore invariant, so that no adaptation to the structure to be produced is possible. Because the reference structure is produced in a separate preparatory step, in addition the processing times are extended and the processes are more complicated overall. For the alignment and positioning of substrates, it is in principle also possible to utilize its already existing surface properties or surface structures, which are detected by means of microscopy, for example, or are known (“correlation stitching”).
The object of the present invention is to ensure a precise positioning and adaptation of the different partial structures against each other during the mentioned production of expanded structures from partial structures in terms of technology as easily as possible, compared to the low requirements for controlling the ambient conditions in the prior art, and obtain consequently high flexibility during the rendering of the structures.